fs: port xattr to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 65efb74c3585..0a8ba82ef1af 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -42,6 +42,7 @@ struct inode;
 struct dentry;
 struct task_struct;
 struct user_namespace;
+struct mnt_idmap;
 
 extern const kernel_cap_t __cap_empty_set;
 extern const kernel_cap_t __cap_init_eff_set;
@@ -271,11 +272,11 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
 }
 
 /* audit system wants to get cap info from files as well */
-int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
+int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 			   const struct dentry *dentry,
 			   struct cpu_vfs_cap_data *cpu_caps);
 
-int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
+int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const void **ivalue, size_t size);
 
 #endif /* !_LINUX_CAPABILITY_H */